1. Field of the Invention
The present invention relates generally to a semiconductor processing tool and, more specifically, to a thermal reactor with improved gas flow distribution.
2. Description of the Related Art
Rapid thermal processing, commonly referred to as ‘RTP’, subjects a substrate to a very brief, intense burst of heat that can go from room temperature to about 1000° C. in seconds. RTP technology is used to change the characteristics of a deposited film or crystal lattice. RTP generally includes processes such as annealing, silicidation and oxidation of a substrate surface.
Generally, an RTP chamber includes a radiant heat source or lamp, a chamber body, a substrate support ring, and a process gas supplying system. The radiant heat source is typically mounted on a top surface of the chamber body so that the energy generated by the heat source radiates upon the substrate supported by the substrate support ring within the chamber body. A quartz window is typically disposed in the top surface of the chamber body to facilitate energy transferring from the heat source to the substrate. An external motor is usually used to rotate the support ring and the substrate to compensate for variations in the radiation energy generated by the lamp that could heat the substrate non-uniformly. A rapid thermal process may be performed at a reduced pressure to get better uniformity.
Processing gases, for example oxygen source in an oxidation process, are usually supplied to the chamber from a gas inlet, and are kept flowing in the chamber by a pumping system connected to chamber. Gas distribution in a conventional chamber is not uniform across the chamber. For example, gas distribution near the gas inlet is different from gas distribution near the pumping port, and gas distribution near the edge region is different from gas distribution near the center region. Although, continuous rotation of the substrate may reduce the non-uniformity of gas distribution, the rotation alone may not be enough as the requirement for uniformity increases.
Therefore, there is a need for a thermal reactor with improved gas flow distribution.